BD Merit - Freelancing, BCS, Bank, Primary, Admission, NTRCA

1 . A two-digit number has 3 in its unit digit. The sum of its digit is one-seventh of the number itself. What is the number?

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Answer: Option B

Explanation:

Since it is in the form of a two digit number, then we can write it as a decimal expansion with a three in the units place.

Let y = 10x + 3

We also know that x + 3 = y⋅17x + 3 = y⋅17

This means if we multiply both sides by 7 we get:

y = 7(x + 3)y = 7(x + 3)

y = 7x + 21y = 7x + 21

Since these are both equal to y, we can set them equal one another to find x, the tens digit value:

7x + 21 = 10x + 37x + 21 = 10x + 3

−3x + 21 = 3−3x + 21 = 3

−3x = −18−3x = −18

x = 6x = 6

y = 10x + 3 = 10(6) + 3 = 63